>I think someone should try banning absolutely everything but emergency vehicles. No cars, no taxis, no vans, no trucks. Only cargo bikes, hand carts and maybe palanquins.

This is honestly crazy. No modern city in the world could function this way. How is cargo going to get moved around? You can't stock a supermarket with cargo bikes, and even in a dense, walkable city like Tokyo where I live, lots of cargo needs to be moved around, especially to stores, but also for cargo deliveries to other businesses and homes. And with no trucks or vans, how do you do stuff like building construction and repair?

Sure, you could get rid of private cars, and even taxis, and reduce 75-95% of the traffic on the roads, then make the roads narrower, add bike lanes, etc., but you can't just keep out cargo vehicles. No one's going to build a skyscraper or large apartment building using cargo bikes and hand carts.

There’d be a revolt. You might be able to get away with doing this in some small area, maybe a city block or two. But anything more than that is just begging for a backlash from the local population.

My city, Utrecht, in the Netherlands is quite close this. No cars in the city center, no diesel vans for delivery, only busses and taxis can drive in certain roads in the center, bikes have priority on most roads cars can drive outside the center, mow they are reducing the speed limit to 30km/h everywhere in the city (following Amsterdam on this), and they are building a new car-free neighborhood for 40k people with no parking spaces and car roads.

Large swaths of many European cities are like this. Copenhagen has a huge pedestrianized shopping area and it's amazing.

There's this - bloommerwede.nl - it looks awesome.